Transflective type liquid crystal display device and manufacturing method thereof

ABSTRACT

A method of manufacturing a transflective type liquid crystal display device includes forming an organic film having different film thicknesses on a passivation film covering a TFT, etching the passivation film to form a contact hole, etching a reflective electrode and a transmissive electrode formed on the organic film by using a resist pattern having different film thicknesses, removing, by ashing, a thin film portion of the resist pattern, and a thin film portion of the organic film exposed from the transmissive electrode to form an opening, etching the reflective electrode by using the resist pattern left after the removal of the thin film portion, and bonding substrates in such a manner that a sealing material in a shape of a frame is arranged in the opening of the organic film.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to a transflective type liquid crystaldisplay device and a manufacturing method thereof.

2. Description of Related Art

In general, a liquid crystal display device is classified into twotypes, i.e., a transmissive type and a reflective type. The transmissivetype liquid crystal display device displays an image by using abacklight placed on the back surface side. The reflective type liquidcrystal display device displays an image by using a reflective plateplaced on the substrate and reflecting ambient light on the surface ofthe reflective plate. The transmissive liquid crystal display device hasa disadvantage that when ambient light is very bright, such as directsunlight, it is difficult to view the display since display light isdarker than the ambient light. On the other hand, the reflective liquidcrystal display device has a disadvantage that visibility decreasessignificantly when ambient light is dark.

In order to compensate these disadvantages, there is proposed atransflective type liquid crystal display device which has both atransmission mode of transmitting a part of light and a reflection modeof reflecting a part of light. In the transflective type liquid crystaldisplay device, an organic film which has uneven (concave or convex)patterns on its surface is coated over an insulating film so as toobtain good scattering characteristics. For example, after coating anorganic film over on an insulating film by spin coating, depressedportions are patterned on the surface of the organic film by aphotolithography process so as to form there uneven patterns.

This organic film is patterned into a predetermined shape within thedisplay area, while the organic film outside the display area isconventionally formed without patterning over the surface. That is, theorganic film is formed from the display area to the frame area which isoutside of the sealing portion. Therefore, the organic film contacts theair at the outside of the sealing portion, and absorbs moisture as thetime passes. Then, the moisture permeates into the panel through theorganic film. This causes disorder of orientation of liquid crystalmolecules when the liquid crystal display device is used for a longperiod of time, so that defective display easily occurs, therebydecreasing reliability.

As a method for solving such a problem, it is effective not to apply theorganic film under the sealing portion. For example, in JapaneseUnexamined Patent Application No. 2003-167258, there is disclosed aliquid crystal display device of a structure having no organic filmunder the sealing portion. In the Japanese Unexamined Patent ApplicationNo. 2003-167258, an opening is formed in the forming area of a sealingmaterial. The opening penetrates an inorganic insulating film covering athin film transistor (TFT) and an organic film layered over theinorganic insulating film, and reaches an interlayer insulating filmapplied between a source line and a gate line. Then, the sealingmaterial is formed in this opening in order to bond opposing substrates.Since this structure makes the sealing material adhere not to theorganic film but to the interlayer insulating film, thereby increasingthe adhesion strength.

Moreover, according to the Japanese Unexamined Patent Application No.2003-167258, at the display area side from the sealing portion, theconnection of the source line is changed to a line formed of the samelayer as that of the gate line, and then the source line is led to theoutside of the sealing portion. Thus, since the source line is oncechanged to the same layer as that of the gate line, the upper part of alead line underlying the sealing portion is protected by the interlayerinsulating film. By virtue of this structure, it is possible to preventthe lead line of the source line from directly contacting the sealingmaterial, thereby maintaining good resistance to corrosion.

However, the structure described in the Japanese Unexamined PatentApplication No. 2003-167258 needs to be provided with a change unit forchanging the source line to the lead line of the same layer as that ofthe gate line. Therefore, in the change unit, a contact hole is formedin the interlayer insulating film in order to connect the source line tothe lead line in the same layer as that of the gate line. Thus, the stepof forming the contact hole in the interlayer insulating film is newlyneeded, thereby increasing the number of manufacturing steps. Moreover,space for the change unit is also newly needed, thereby increasing thewidth of the frame area.

Moreover, according to the Japanese Unexamined Patent Application No.2003-167258, at the process of forming the contact hole for connecting adrain electrode to a pixel electrode, an opening which penetrates theinorganic insulating film and the organic film is formed in the sealingportion. Specifically, after forming an inorganic insulating film whichcovers the TFT, a pattern of an organic film is formed thereon. Dryetching of the inorganic insulating film is performed using this patternof the organic film as a mask. At this time, the interlayer insulatingfilm under the inorganic insulating film is exposed to an etching gas atthe opening. Thus, the interlayer insulating film may be damaged,thereby there is concern that insulation between the lead lines may bedecreased. If the interlayer insulating film is further damaged, thelead line will be exposed to contact the sealing material directly, sothat there is a possibility of the line being broken by corrosion. Thus,there is concern that the reliability may be reduced.

In addition, another method can be considered in which when forming theopening which penetrates the inorganic insulating film and the organicfilm in the sealing portion, patterning of the inorganic insulating filmis performed first, and then, a pattern of the organic film is formedthereon in order to reduce the damage of the interlayer insulating film.However, according to this method, the inorganic insulating film ispatterned separately, thereby increasing the number of the steps ofphotolithography by adding one step. Thus, there is a problem of causingan increase of the manufacturing cost and a lengthening of themanufacturing period.

The present invention has been contrived to solve the problem describedabove, and an object thereof is to provide a transflective type liquidcrystal display device which can improve the reliability withoutincreasing the number of photolithography steps, and to provide amanufacturing method thereof.

SUMMARY OF THE INVENTION

In accordance with one example of the present invention, there isprovided a method of manufacturing a transflective type liquid crystaldisplay device that includes forming a thin film transistor over a firstsubstrate, forming an inorganic insulating film to cover the thin filmtransistor, forming an organic film having different film thicknesses onthe inorganic insulating film, etching the inorganic insulating filmexposed from the organic film, to form a contact hole, forming atransmissive electrode and a reflective electrode as films on theorganic film in order, forming a resist pattern having different filmthicknesses on the reflective electrode and etching the reflectiveelectrode and the transmissive electrode, removing, by ashing, a thinfilm portion of the resist pattern and a thin film portion of theorganic film, exposed from the transmissive electrode, to form anopening, forming a pixel electrode connecting to the thin filmtransistor through the contact hole by etching the reflective electrodeby using the resist pattern left after the removal of the thin filmportion, and bonding the first substrate and a second substrate arrangedoppositely to the first substrate in such a manner that a sealingmaterial in a shape of a frame surrounding a display area is arranged inthe opening of the organic film.

In accordance with another example of the present invention, there isprovided a transflective type liquid crystal display device thatincludes a first substrate including a thin film transistor formedthereover, a second substrate arranged oppositely to the firstsubstrate, a sealing material, formed in a shape of a frame surroundinga display area, to bond the first substrate and the second substrate, aninorganic insulating film to cover the thin film transistor over thefirst substrate, an organic film formed on the inorganic insulatingfilm, and a pixel electrode including a transmissive electrode providedon the organic film and a reflective electrode provided on a part of thetransmissive electrode, and the pixel electrode connecting to the thinfilm transistor through a contact hole penetrating the organic film andthe inorganic insulating film. The organic film includes a thick filmportion provided under the reflective electrode, a thin film portionformed outside of the transmissive electrode and having a film thicknessthinner than a film thickness of the thick film portion, and an opening.The sealing material is arranged in the opening.

The present invention is able to provide a transflective type liquidcrystal display device which can improve the reliability withoutincreasing the number of photolithography steps, and to provide amanufacturing method thereof.

The above and other objects, features and advantages of the presentinvention will become more fully understood from the detaileddescription given hereinbelow and the accompanying drawings which aregiven by way of illustration only, and thus are not to be considered aslimiting the present invention.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a front view showing the structure of a liquid crystal displaydevice according to a present embodiment;

FIG. 2 is a plan view showing the pixel structure of the liquid crystaldisplay panel according to the present embodiment;

FIG. 3 is a III-III cross-sectional view of FIG. 2;

FIG. 4 is a cross-sectional view cut through the line IV-IV in FIG. 1;

FIG. 5 is a cross-sectional view cut through the line V-V in FIG. 1;

FIGS. 6A to 6C are cross-sectional views showing one manufacturingprocess of the TFT array substrate according to the present embodiment;

FIGS. 7A to 7C are cross-sectional views showing one manufacturingprocess of the TFT array substrate according to the present embodiment;

FIGS. 8A to 8C are cross-sectional views showing one manufacturingprocess of the TFT array substrate according to the present embodiment;

FIGS. 9A to 9C are cross-sectional views showing one manufacturingprocess of the TFT array substrate according to the present embodiment;

FIGS. 10A to 10C are cross-sectional views showing one manufacturingprocess of the TFT array substrate according to the present embodiment;

FIGS. 11A to 11C are cross-sectional views showing one manufacturingprocess of the TFT array substrate according to the present embodiment;

FIGS. 12A to 12C are cross-sectional views showing one manufacturingprocess of the TFT array substrate according to the present embodiment,and

FIGS. 13A to 13C are cross-sectional views showing one manufacturingprocess of the TFT array substrate according to the present embodiment.

DESCRIPTION OF THE EXEMPLARY EMBODIMENTS

Referring to FIG. 1, a transflective type liquid crystal display deviceaccording to the present Embodiment will now be described. FIG. 1 is afront view showing the structure of a liquid crystal display device.

The liquid crystal display device of the present invention includes aliquid crystal display panel 100. In the liquid crystal display panel100, a thin film transistor array substrate (TFT array substrate) 1 andan opposing substrate 2 are oppositely arranged.

A display area 41 and a frame area 42 surrounding the display area 41are provided to the TFT array substrate 1. A plurality of gate lines(scanning signal lines) 6 and a plurality of source lines (displaysignal lines) 5 are formed in the display area 41. The plurality of gatelines 6 are provided in parallel. Likewise, the plurality of sourcelines 5 are provided in parallel. The gate lines 6 and source lines 5are formed to cross each other. The gate lines 6 and source lines 5 areorthogonal. Moreover, an area surrounded by adjacent gate lines 6 andsource lines 5 is a pixel 49. Accordingly in the TFT array substrate 1,pixels 49 are arranged in matrix.

Furthermore, a flexible substrate 47 on which a control circuit 45 isloaded and a flexible substrate 48 on which a control circuit 46 isloaded are connected to a frame area 42 of the TFT array substrate 1. Agate line 6 extends from a display area 41 to the frame area 42. Thegate line 6 is connected to the control circuit 46 through a gate lineterminal 44, at the end of the TFT array substrate 1. Similarly, asource line 5 extends from the display area 41 to the frame area 42. Thesource line 5 is connected to the control circuit 45 through a sourceline terminal 43, at the end of the TFT array substrate 1.

Various signals from outside are supplied to the control circuits 45 and46. The control circuit 46 supplies a gate signal (scanning signal) tothe gate line 6 according to an external control signal. By the gatesignal, the gate lines 6 are selected sequentially. The control circuit45 supplies a display signal (source signal) to the source lines 5according to an external control signal or display data. This enables tosupply a display voltage according to the display data to each of thepixels 49. The control circuit 45 may be separately loaded on the liquidcrystal display panel 100, the flexible substrate 47, and a flexibleprinted circuit (FPC) (not shown). Similarly, the control circuit 46 maybe separately loaded on the liquid crystal display panel 100, theflexible substrate 48, and the FPC. Furthermore, a part of the controlcircuits 45 and 46 may be formed on the TFT array substrate 1.

Inside the pixel 49, at least one TFT 50 is formed. The TFT 50 is placednear the intersection of the source line 5 and the gate line 6. Forexample, this TFT 50 supplies the display voltage to a pixel electrode.That is, by the gate signal from the gate line 6, the TFT 50, which is aswitching device, is turned on. This enables to apply the displayvoltage to the pixel electrode connected to a drain electrode of the TFT50 from the source line 5. Moreover, an electric field according to thedisplay voltage is generated between the pixel electrode and an opposingelectrode. Note that an alignment layer (not shown) is formed over thesurface of the TFT array substrate 1. Detailed structure in a pixel 49will be described later.

Meanwhile, an opposing substrate 2 is for example a color filtersubstrate and placed to the visible side. Over the opposing substrate 2,a color filter, black matrix (BM), an opposing electrode, an alignmentlayer, and so on are formed. Note that the opposing electrode may beplaced to the TFT array substrate 1 side. The TFT array substrate 1 andthe opposing substrate 2 are bonded each other by a sealing material 31.The sealing material 31 is formed in the shape of a frame surroundingthe display area 41. In addition, a liquid crystal layer is held betweenthe TFT array substrate 1 and the opposing substrate 2. Morespecifically, liquid crystal is filled between the TF array substrate 1and the opposing substrate 2. Further, a polarizing plate andretardation film or the like are provided to the outside surface the TFTarray substrate 1 and the opposing substrate 2. Moreover, a backlightunit or the like is provided to the non-visible side of the liquidcrystal display panel 100.

The liquid crystal is driven by the electric field between the pixelelectrode and the opposing electrode. That is, an alignment direction ofthe liquid crystal between the substrates changes. This changes thepolarization state of the light passing through the liquid crystallayer. To be more specific, the light that has passed the polarizingplate and became a linearly polarized light changes its polarizationstate by the liquid crystal layer. More specifically, in a transparentarea, the light from the backlight unit becomes a linearly polarizedlight by the polarizing plate provided to the TFT array substrate 1side. Furthermore, by passing through the retardation film of the TFTarray substrate 1 side, the liquid crystal layer, and the retardationfilm of the opposing substrate 2 side, the linearly polarized lightchanges its polarization state. On the other hand, in a reflection area,an outside light entered from the visible side of the liquid crystaldisplay panel 100 becomes a linearly polarized light by the polarizingplate of the opposing substrate 2. Then, by passing through theretardation film of the opposing substrate 2 and the liquid crystallayer back and forth, this light changes its polarization state.

Thus, the amount of light passing through the polarizing plate of theopposing substrate 2 side varies according to the polarization state.More specifically, among transmitted light transmitting from thebacklight unit through the liquid crystal panel 100 and reflected lightreflected at the liquid crystal panel 100, the amount of light passingthrough the polarizing plate of the visible side varies. The alignmentdirection of the liquid crystal varies according to the applied displayvoltage. Therefore, by controlling the display voltage, the amount oflight passing through the polarizing plate of the visible side can bechanged. That is, by varying the display voltage to each pixel, adesired image can be displayed.

Next, a pixel structure of the liquid crystal display panel 100 will bedescribed with reference to FIGS. 2 and 3. FIG. 2 is a plan view showingthe pixel structure of the liquid crystal display panel 100 according tothe present Embodiment. FIG. 3 is a III-III cross-sectional view of FIG.2. FIG. 2 is a plan view showing one of the pixels 49 of the liquidcrystal display panel 100. A plurality of such pixels 49 are arranged inmatrix in the liquid crystal display panel 100. In FIG. 2, only the TFTarray substrate 1 side of the liquid crystal display panel 100 isillustrated, and the opposing substrate 2 side of it is not shown.

As shown in FIGS. 2 and 3, the TFT array substrate 1 includes asubstrate 3 which is transparent and insulated, such as glass orplastic, and on which the gate line 6 and a gate electrode 7 are formed.The gate electrode 7 is arranged branching from the gate line 6 in eachpixel 49. Moreover, on the substrate 3, a common line 12 is formed ofthe same layer as that of the gate line 6. The common line 12 isprovided away from the gate line 6 and extends in parallel to the gateline 6. That is, the common line 12 is arranged between the adjacentgate lines 6. The common line 12 is broadly formed in the pixel 49, andserves as a storage capacitor electrode for forming a storagecapacitance enabling stable display. In FIG. 3, in the reflective area,the storage capacitance is respectively formed between the common line12 and a drain electrode 9 mentioned later and between the drainelectrode 9 and a pixel electrode 10 mentioned later. The storagecapacitor stores a drive voltage from a TFT 50 connected to each pixel49 even after the TFT 50 has been turned off.

In this case, the gate line 6, the gate electrode 7, and the common line12 are formed of an Al alloy, for example. It is also possible for themto be formed of a Cu alloy, a Mo alloy, an Ag alloy, or a Cr alloy, andalternatively formed of a laminated multi-layer film composed of such analloy film and a film, layered beneath the alloy film, which strengthensadhesion to the base, or a laminated multi-layer film composed of suchan alloy film and a conductive film, layered over the alloy film, whichhas good contact characteristics with a transparent conductive film.

There is provided a gate insulating film 15 to cover the gate line 6,the gate electrode 7, and the common line 12. The gate insulating film15 is formed of silicon nitride (SiN), for example. On the opposite sideof the gate electrode 7 with respect to the gate insulating film 15, asemiconductor layer 14 is provided. The semiconductor layer 14 is formedof amorphous silicon, for example.

On the semiconductor layer 14, there are formed the source line 5, asource electrode 8, and the drain electrode 9. The source electrode 8 isarranged branching from the source line 5 in each pixel 49. The drainelectrode 9 is provided away from the source electrode 8, on thesemiconductor layer 14. That is, the source electrode 8 and the drainelectrode 9 are oppositely arranged on the semiconductor layer 14. Inaddition, an ohmic contact layer 16 is respectively formed between thesource electrode 8 and the semiconductor layer 14 and between the drainelectrode 9 and the semiconductor layer 14. The ohmic contact layer 16is provided in the area where the source electrode 8 and thesemiconductor layer 14 overlap each other. Similarly, the ohmic contactlayer 16 is provided in the area where the drain electrode 9 and thesemiconductor layer 14 overlap each other. In the semiconductor layer14, the area not covered with the source electrode 8 or the drainelectrode 9 serves as a channel 4 of the TFT 50.

In this case, the source line 5, the source electrode 8, and the drainelectrode 9 are formed of Cr, for example. It is also possible for themto be formed of a low resistance metal, such as a Mo alloy, an Al alloy,and an Ag alloy, and alternatively formed of a laminated multi-layerfilm composed of such a low resistance metal and a conductive film,layered beneath the low resistance metal, which has good contactcharacteristics with the ohmic contact layer 16, or a laminatedmulti-layer film composed of such a low resistance metal and aconductive film, layered over the low resistance metal, which has goodcontact characteristics with a transparent conductive film.

There is provided a passivation film 17 to cover the source line 5, thesource electrode 8, and the drain electrode 9. That is, the passivationfilm 17 covers the TFT 50. The passivation film 17 is formed of aninorganic insulating film, such as SiN. Furthermore, there is applied anorganic film 18 over the passivation film 17. On the drain electrode 9of the TFT 50, a contact hole 13 is formed in the organic film 18 andthe passivation film 17. That is, the contact hole 13 penetrates theorganic film 18 and the passivation film 17, and reaches the drainelectrode 9 of the TFT 50.

The organic film 18 is an organic resin film serving as a base layer forforming the pixel electrode 10, and planarizes the unevenness on thesubstrate 3 produced by the source line 5, the gate line 6, the commonline 12, the TFT 50, etc. Since the liquid crystal display deviceaccording to the present Embodiment is a transflective type liquidcrystal display device, the pixel 49 includes a transmissive area and areflective area. In the reflective area, uneven patterns are formed onthe surface of the organic film 18 so that reflected lights may have asuitable dispersed distribution.

On the organic film 18, there is provided the pixel electrode 10connected to the drain electrode 9 through the contact hole 13. Thepixel electrode 10 has a single layer structure of a transmissiveelectrode 10 a in the transmissive area, and a laminated multi-layerstructure where a reflective electrode 10 b is layered on thetransmissive electrode 10 a in the reflective area. That is, thetransmissive electrode 10 a is provided in both the transmissive areaand the reflective area. In this case, the transmissive electrode 10 ais formed of a transparent conductive film, such as an ITO. Thetransmissive electrode 10 a is not limited to the ITO, and it may beformed of other transparent conductive film, such as an ITSO and an IZO.On the other hand, the reflective electrode 10 b is provided only in thereflective area. In this case, the reflective electrode 10 b is formedof a reflective conductive film, such as an AL alloy. It is alsopossible for the reflective electrode 10 b to be formed of a highreflective metal, such as an Ag alloy, or formed of a reflectiveconductive film such as a laminated multi-layer film composed of thehigh reflective metal and a contact metal layered beneath the highreflective metal. Alternatively, it may have a structure where atransparent conductive film is coated on the reflective electrode 10 bin order to prevent burn-in.

In the present Embodiment, as shown in FIG. 3, the film thickness of theorganic film 18 at the area covered with the pixel electrode 10 isthicker than that at the area not covered with the pixel electrode 10.That is, in the organic film 18, a thick film portion 18 a is formed inthe area covered with the pixel electrode 10 and a thin film portion 18c is formed in the area not covered with the pixel electrode 10. Thereason for this state will be mentioned later. There is provided analignment film 19 for aligning a liquid crystal 30, on the pixelelectrode 10.

In the opposing substrate 2, there is formed a black matrix 22 on thesurface of a substrate 21 to be opposite to the TFT array substrate 1.The black matrix 22 is made of a metal such as a pigment or chromium andis for shielding lights. The black matrix 22 is provided to be oppositeside to the source line 5 and the gate line 6 and is in a grid-likeconfiguration. Then, a color material 23 composed of a pigment or dye isformed to fill between the black matrices 22. The color material 23 is acolor filter of R (red), G (green), and B (blue).

Further, there is formed an overcoat 24 to cover the black matrix 22 andthe color material 23. The overcoat 24 is formed to be thicker in thereflective area than in the transmissive area. Thereby, the space (gap)between the TFT array substrate 1 and the opposing substrate 2 in thetransmissive area can be broader than that in the reflective area. Thereare layered an opposing electrode 25 and an alignment film 29 on theovercoat 24 in this order. The opposing electrode 25 produces anelectric field between itself and the pixel electrodes 10 of the TFTarray substrate 1, so as to drive the liquid crystal 30.

Now, referring to FIGS. 4 and 5, the structure of the sealing portionwill be described. FIGS. 4 and 5 are cross-sectional views showing thestructure of the periphery of the sealing portion of the liquid crystaldisplay panel 100 according to the present Embodiment. FIG. 4 is across-sectional view cut through the line IV-IV in FIG. 1, and shows theperiphery of the sealing portion at the side of the gate line terminal44. FIG. 5 is a cross-sectional view cut through the line V-V in FIG. 1,and shows the periphery of the sealing portion at the side of the sourceline terminal 43.

In FIG. 4, there is formed the gate line 6 on the substrate 3 of the TFTarray substrate 1. The gate insulating film 15 and the passivation film17 are coated in this order to cover the gate line 6. In FIG. 5, thesource line 5 is formed on the gate insulating film 15 provided over thesubstrate 3. The passivation film 17 is formed to cover the source line5.

In FIGS. 4 and 5, the organic film 18 is formed on the passivation film17. According to the present Embodiment, the organic film 18 under andaround the sealing material 31 is removed to provide an opening 18 d.The opening 18 d is formed to be broader than the sealing material 31.Therefore, the opening 18 d, which is broader than the sealing material31, is provided to be in the shape of a frame surrounding the displayarea 41. According to the present Embodiment, since the passivation film17 provided under the opening 18 d is not affected by a film thicknessloss caused by etching etc., its film thickness is approximately thesame as that of the passivation film 17 provided under the thin filmportion 18 c or the thick film portion 18 a.

FIGS. 4 and 5 show cross-sectional structure of the area where the pixelelectrode 10 is not provided on the organic film 18 at the display area41 side from the sealing material 31. In this case, the thin filmportion 18 c is arranged at the display area 41 side from the sealingmaterial 31 as well as the structure of the pixel 49 shown in FIG. 3.Moreover, the thin film portion 18 c is also arranged at the frame area42 side from the sealing material 31.

The TFT array substrate 1 described above adheres to the opposingsubstrate 2 through the sealing material 31. At the side of the opposingsubstrate 2, the sealing material 31 is arranged in the pattern of theblack matrix 22 and adheres to the opposing electrode 25. On the otherhand, at the side of the TFT array substrate 1, the sealing material 31is arranged in the opening 18 d provided in the organic film 18. Thatis, the sealing material 31 adheres to the passivation film 17 in theopening 18 d. Thereafter, the liquid crystal 30 is filled in the spacesurrounded by the TFT array substrate 1, the opposing substrate 2, andthe sealing material 31. In addition, the alignment film 19 is providedon the surface of the TFT array substrate 1 contacting the liquidcrystal 30, and the alignment film 29 is provided on the surface of theopposing substrate 2 contacting the liquid crystal 30. That is, thealignment films 19 and 29 are arranged at the inner side from thesealing material 31.

Now, a manufacturing method of the transflective type liquid crystaldisplay device according to the present Embodiment will be describedwith reference to FIGS. 6A to 6C through 13A to 13C. FIGS. 6A to 6Cthrough 13A to 13C are cross-sectional views showing one manufacturingprocess of the TFT array substrate according to the present Embodiment.FIGS. 6A, 7A, 8A, 9A, 10A, 11A, 12A, and 13A are cross-sectional viewsshowing the inside of the pixel 49, corresponding to the III-III sectionin FIG. 2. FIGS. 6B, 7B, 8B, 9B, 10B, 11B, 12B, and 13B arecross-sectional views showing the periphery of the sealing portion atthe side of the gate line terminal 44, corresponding to the IV-IVsection in FIG. 1. FIGS. 6C, 7C, 8C, 9C, 10C, 11C, 12C, and 13C arecross-sectional views showing the periphery of the sealing portion atthe side of the source line terminal 43, corresponding to the V-Vsection in FIG. 1.

First, with reference to FIGS. 6A to 6C, a manufacturing process relatedto a first photolithography step will be described. To begin with, anelectrode film serving as the gate line 6, the gate electrode 7, and thecommon line 12 is formed on the substrate 3. For example, by the spattermethod, etc., an electrode film of an Al alloy, etc. is formed all overthe substrate 3. The electrode film is not limited to be formed of theAl alloy, and it may be formed of a Cu alloy, a Mo alloy, an Ag alloy,or a Cr alloy, and alternatively formed of a laminated multi-layer filmcomposed of such an alloy film and a film, layered beneath the alloyfilm, which strengthens adhesion to the base, or a laminated multi-layerfilm composed of such an alloy film and a conductive film, layered overthe alloy film, which has good contact characteristics with atransparent conductive film. Next, a resist pattern is formed on theelectrode film by the process of the first photolithography step. Theelectrode film is patterned by the wet etching method, etc. Then,removing the resist pattern, the gate line 6, the gate electrode 7, andthe common line 12 are formed as shown in FIGS. 6A to 6C.

Next, with reference to FIGS. 7A to 7C, a manufacturing process relatedto from a step of forming the gate insulating film 15 through a secondphotolithography step will be described. The gate insulating film 15 isformed to cover the gate line 6, the gate electrode 7, and the commonline 12. For example, by the plasma CVD method, SiN is formed as thegate insulating film 15 all over the substrate 3. Then, thesemiconductor layer 14 and the ohmic contact layer 16 are formed on thegate insulating film 15 in this order. For example, by the plasma CVDmethod, after forming an amorphous silicon film as the semiconductorlayer 14 all over the substrate 3, an n-type amorphous silicon film towhich impurities such as phosphorus (P) is added is formed as the ohmiccontact layer 16 all over the substrate 3.

Then, a resist pattern is formed on the ohmic contact layer 16 by theprocess of the second photolithography step. The ohmic contact layer 16and the semiconductor layer 14 are patterned in the shape of an islandby dry etching etc. Removing the resist pattern, the semiconductor layer14 and the ohmic contact layer 16 are formed on the opposite side of thegate electrode 7 with respect to the gate insulating film 15 as shown inFIG. 7A. At this time, on the periphery of the sealing portion at theside of the gate line terminal 44, the gate line 6 is covered with thegate insulating film as shown in FIG. 7B. On the periphery of thesealing portion at the side of the source line terminal 43, the gateinsulating film 15 is coated over the substrate 3 as shown in FIG. 7C.

Now, with reference to FIGS. 8A to 8C, a manufacturing process relatedto a third photolithography step will be described. An electrode filmserving as the source line 5, the source electrode 8 and the drainelectrode 9 is formed to cover the semiconductor layer 14 and the ohmiccontact layer 16. For example, by the spatter method etc., an electrodefilm of Cr, etc. is formed all over the substrate 3. The electron filmis not limited to be formed of the Cr, and it may be formed of a lowresistance metal, such as a Mo alloy, an Al alloy, an Ag alloy, etc.,and alternatively formed of a laminated multi-layer film composed ofsuch a low resistance metal and a conductive film, layered beneath thelow resistance metal, which has good contact characteristics with theohmic contact layer 16, or a laminated multi-layer film composed of sucha low resistance metal and a conductive film, layered over the lowresistance metal, which has good contact characteristics with atransparent conductive film. Next, a resist pattern is formed on theelectrode film by the process of the third photolithography step. Then,an electrode film is patterned by the wet etching method etc. Thereby,the source line 5, the source electrode 8, and the drain electrode 9 areformed. Thereafter, the ohmic contact layer 16, which is exposed to thesurface, without being covered with the source electrode 8 or the drainelectrode 9, is removed by dry etching etc. Thereby, the semiconductorlayer 14 between the source electrode 8 and the drain electrode 9 isexposed to form the channel 4. Then, removing the resist pattern, thestructure as shown in FIGS. 8A to 8C can be obtained.

Next, with reference to FIGS. 9A to 9C, a manufacturing process relatedto from a step of forming the passivation film 17 through a fourthphotolithography step will be described. The passivation film 17 isformed to cover the source line 5, the source electrode 8, and the drainelectrode 9. For example, by the plasma CVD method, SiN is formed as thepassivation film 17 all over the substrate 3. The organic film 18 havingphotosensitivity is applied on the passivation film 17. Then, the fourthphotolithography step is performed to pattern the organic film 18. Atthis time, according to the present Embodiment, the organic film 18including the thick film portion 18 a, a thin film portion 18 b and thecontact hole 13 is formed by using multi level exposure, such as halftone and gray tone.

Specifically, in the area used as the contact hole 13, the organic film18 is removed to expose the passivation film 17. In the area directlyunder or around the sealing material 31 (sealing portion periphery area32), the thin film portion 18 b whose film thickness is thin is formedby using the multi level exposure as shown in FIGS. 9B and 9C. At thistime, conditions of the fourth photolithography step are adjusted sothat a film thickness d1 of the thin film portion 18 b may be thinnerthan a film thickness d2 which is removed by plasma ashing mentionedlater. In the area except for the contact hole 13 and the thin filmportion 18 b, the thick film portion 18 a whose film thickness isthicker than that of the thin film portion 18 b is formed. On thereflective area in the thick film portion 18 a, uneven patterns areformed on the surface by partially exposing. In the fourthphotolithography step, as mentioned above, the organic film 18 which hasdifferent film thicknesses is formed by using a first multi-levelexposure.

Then, using this organic film 18 as a mask, the passivation film 17 ispatterned by the dry etching method etc. Thereby, the passivation film17 in the area used as the contact hole 13 is removed to expose thedrain electrode 9 as shown in FIG. 9A.

Next, with reference to FIGS. 10A to 10C, a manufacturing processrelated to from a step of forming a film of the transmissive electrode10 a and the reflective electrode 10 b through a fifth photolithographystep will be described. A transparent conductive film serving as thetransmissive electrode 10 a is formed on the organic film 18, andfurther, a reflective conductive film serving as the reflectiveelectrode 10 b is formed thereon. For example, by the spatter method, anamorphous ITO as the transparent conductive film, and an Al alloy filmas the reflective conductive film are formed all over the substrate 3 inthis order. ITSO, IZO, etc. may be used for the transparent conductivefilm serving as the transmissive electrode 10 a. Moreover, it is alsopossible to use a high reflective metal, such as an Ag alloy, or alaminated multi-layer film composed of such an alloy film and a contactmetal film layered beneath the alloy film, for the reflective conductivefilm serving as the reflective electrode 10 b. Thereby, the contact hole13 is covered with the transmissive electrode 10 a and the reflectiveelectrode 10 b.

Then, after applying resist (photosensitive resin) over the reflectiveconductive film by the spin coat method etc., a resist pattern 35 whichhas different film thicknesses is formed by the process of the fifthphotolithography step. The resist pattern 35 includes a thick filmportion 35 a having a film thickness d3 in the reflective area and athin film portion 35 b having a film thickness d4 in the transmissivearea. That is, using the multi-level exposure, the resist pattern 35 isformed so that the film thickness d4 of the transmissive area may bethinner than the film thickness d3 of the reflective area. In the fifthphotolithography step, as mentioned above, the resist pattern 35 whichhas different film thicknesses is formed by using a second multi-levelexposure. Thereby, the structure shown in FIGS. 10A, 10B, and 10C can beobtained, where the resist pattern 35 is not formed in the sealingportion periphery area 32 as shown in FIGS. 10B and 10C.

Now, with reference to FIGS. 11A to 11C, a manufacturing process relatedto a step of etching the transmissive electrode 10 a and the reflectiveelectrode 10 b will be described. Using the resist pattern 35 as a mask,patterning is performed for the reflective electrode 10 b and thetransmissive electrode 10 a in this order by the well-known wet etchingmethod etc. Thereby, as shown in FIGS. 11A to 11C, the transmissiveelectrode 10 a and the reflective electrode 10 b which do not overlapwith the resist pattern 35 are removed.

Next, with reference to FIGS. 12A to 12C, a manufacturing processrelated to an ashing step will be described. After etching thetransmissive electrode 10 a and the reflective electrode 10 b, the thinfilm portion 35 b of the resist pattern 35 is removed by ashing, such asa plasma ashing method. Then, the film thickness of the thick filmportion 35 a of the resist pattern 35 becomes thin and the patternremains as a resist pattern 35 c. That is, as shown in FIG. 12A, theresist pattern 35 from which the thin film portion 35 b has been removedserves as the resist pattern 35 c. Simultaneously, according to thepresent Embodiment, the thin film portion 18 b of the organic film 18,exposed from the transmissive electrode 10 a, is removed to form theopening 18 d as shown in FIGS. 12B and 12C. That is, ashing is performedfor the organic film 18 in the area exposed from the transmissiveelectrode 10 a, by utilizing ashing of the resist pattern 35. Then, thefilm thickness d2 of the thick film portion 18 a of the organic film 18,exposed from the transmissive electrode 10 a, becomes thin and theportion remains as a thin film portion 18 c.

As mentioned above, the thin film portion 35 b of the resist pattern 35is removed by ashing, and the thin film portion 18 b of the organic film18, exposed from the transmissive electrode 10 a, is removed by ashingto form the opening 18 d according to the present Embodiment. That is,by this ashing, the thin film portion 18 b is removed and the opening 18d is formed in the sealing portion periphery area 32. Since the opening18 d is formed in the sealing portion periphery area 32 by such amethod, the passivation film 17 in the opening 18 d is not damaged byetching etc. Therefore, the passivation film 17 in the opening 18 d doesnot have a film thickness loss caused by the damage, and has the samefilm thickness as that of the passivation film 17 in the area coveredwith the organic film 18. As shown in FIG. 12B, under the opening 18 d,the lead line of the gate line 6 is covered with this passivation film17 and the gate insulating film 15. Moreover, as shown in FIG. 12C,under the opening 18 d, the lead line of the source line 5 is coveredwith the passivation film 17.

Now, with reference to FIGS. 13A to 13C, a manufacturing process relatedto from a step of etching the reflective electrode 10 b through a stepof removing the resist pattern 35 will be described. After ashing,patterning is performed for the reflective electrode 10 b with using theresist pattern 35 c as a mask, by the well-known wet etching method etc.Thereby, the reflective electrode 10 b in the transmissive area isremoved. That is, as shown in FIG. 13A, the transmissive electrode 10 ain the transmissive area is exposed to form the pixel electrode 10.Since a method suitable for the material of the reflective electrode 10b is used for the etching at this time, the passivation film 17 exposedin the opening 18 d is not damaged by the etching. Then, the resistpattern 35 c is removed and an annealing treatment is performed tocrystallize an amorphous ITO of the reflective electrode 10 b.Consequently, the structure shown in FIGS. 13A to 13C can be obtained.Through the steps described above, the TFT array substrate 1 accordingto the present Embodiment is completed.

The alignment film 19 is formed over the TFT array substrate 1 producedin the way described above. Moreover, the alignment film 29 is similarlyformed over the opposing substrate 2 which has been produced separately.Thereafter, an orientation treatment (rubbing treatment) is performedfor the alignment films 19 and 29 to produce a micro roughness in onedirection on the contacting surface with liquid crystal. Next, thesealing material 31 is applied to bond the TFT array substrate 1 and theopposing substrate 2. Concretely, at the side of the TFT array substrate1, the TFT array substrate 1 and the opposing substrate 2 are bonded insuch a manner that the sealing material 31 is arranged in the opening 18d of the organic film 18. That is, the sealing material 31 is bonded tothe passivation film 17 in the opening 18 d.

Since the organic film 18 extending from the display area 41 does notextend to the outside of the sealing material 31, it is possible toprevent moisture from permeating through the organic film 18. At thistime, under the sealing material 31, the lead line of the gate line 6 iscovered with the gate insulating film 15 and the passivation film 17which has not been damaged. The lead line of the source line 5 iscovered with the passivation film 17 which has not been damaged.Accordingly, it is possible to suppress an insulation decrease betweenthe lead lines of the gate line 6 or the source line 5. Moreover, it ispossible to deter the lead line being broken by corrosion caused bydirectly contacting the sealing material 31. Thus, the reliability ofthe liquid crystal display device can be enhanced.

After bonding the TFT array substrate 1 and the opposing substrate 2,the liquid crystal 30 is injected from the liquid crystal inlet by thevacuum injection method, etc. Then, the inlet of the liquid crystal issealed. Thus, the liquid crystal display panel 100 according to thepresent Embodiment is completed.

In the present Embodiment, as mentioned above, after applying theorganic film 18 over the passivation film 17, the contact hole 13 isformed on the organic film 18 on the drain electrode 9 and the thin filmportion 18 b is formed in the sealing portion periphery area 32, byusing the first multi-level exposure. Then, the passivation film 17 isetched by using the organic film 18 as a mask, to form the contact hole13 which reaches the drain electrode 9. After forming the transmissiveelectrode 10 a and the reflective electrode 10 b as films over theorganic film 18 in this order, the resist pattern 35 having differentfilm thicknesses is formed using the second multi-level exposure, andthen, the transmissive electrode 10 a and the reflective electrode 10 bare etched. Thereafter, ashing is performed to remove the thin filmportion 35 b of the resist pattern 35, and the thin film portion 18 b ofthe organic film 18, exposed from the transmissive electrode 10 a,thereby forming the opening 18 d. Thus, the opening 18 d can be formedin the organic film 18 of the sealing portion periphery area 32 withoutincreasing the number of photolithography steps. Therefore, moisturepermeation through the organic film 18 can be prevented. In the sealingportion periphery area 32, only the organic film 18 is removed by ashingand the passivation film 17 remains without being damaged. Accordingly,it is possible to suppress an insulation decrease between the lead linesof the gate line 6 or the source line 5, and to prevent the lead linefrom being broken. Therefore, the transflective type liquid crystaldisplay device capable of improving the reliability without increasingthe number of photolithography steps, and a manufacturing method thereofcan be provided.

In the Embodiment described above, while the case of the organic film 18under the sealing material 31 being removed by the width larger than thewidth of the sealing material 31 in order to remain the organic film 18outside the sealing material 31 is explained as an exemplification, itis not limited to such a case. The organic film 18 outside (frame area42 side) of the sealing material 31 may be removed. In this case, if thethin film portion 18 b of the organic film 18 in the area to be removedis formed similarly to the sealing portion periphery area 32 by thefirst multi-level exposure, it is possible to perform removing by ashingafter the second multi-level exposure. Furthermore, while the sealingmaterial 31 is arranged inside the opening 18 d, it is also possible forthe sealing material 31 to be arranged to straddle the organic film 18outside the opening 18 d. That is, if the end of the organic film 18extending from the display area 41 is located inside the outer end ofthe sealing material 31, moisture permeation through the organic film 18can be prevented.

Moreover, although a step (unevenness) is provided in the overcoat 24 ofthe opposing substrate 2 in order to make the gaps in the transmissivearea and the reflective area be different, it is also preferable toprovide the step not on the side of the opposing substrate 2 but on theside of the TFT array substrate 1. For example, the film thickness ofthe organic film 18 in the transmissive area may be different from thatin the reflective area. In this case, a thin film portion is formed inthe transmissive area by the first multi-level exposure when forming theorganic film 18. The film thickness of the thin film portion formed inthe transmissive area may be the same as that of the thin film portion18 b of the sealing portion periphery area 32, and alternatively theymay be different from each other. That is, film thickness of the thinfilm portion formed in the transmissive area can be appropriately set updepending upon a required step (unevenness). Since this thin filmportion is covered with the transmissive electrode 10 a, it remains as athin film portion without being removed by ashing. In addition, althoughthe thick film portion 18 a is formed by the first multi-level exposurein the area except for the transmissive area, the reflective area, thecontact hole 13, and the sealing portion periphery area 32, it is alsopossible to form the thin film portion 18 b similarly to the sealingportion periphery area 32. Since this thin film portion 18 b is notcovered with the transmissive electrode 10 a, it can be removed byashing to form the opening 18 d.

Furthermore, although patterning of the source line 5, the sourceelectrode 8, and the drain electrode 9 is performed in thephotolithography step which is different from the photolithography stepfor patterning of the semiconductor layer 14, it is also preferable toperform the patterning for them in the same photolithography step byusing the multi-level exposure. In that case, the structure is in such amanner that the ohmic contact layer 16 and the semiconductor layer 14are formed approximately all over the area under the source line 5, thesource electrode 8, and the drain electrode 9. Then, the multi-levelexposure is performed for the forming area of the channel 4.

In addition, while the case of forming a TFT of channel etching type hasbeen explained above as an exemplification, an etching stopper type TFT,or a top gate type TFT using polysilicon for the semiconductor layer 14may also be used.

The above explanation is to describe the embodiments of the presentinvention and the present invention is not limited to the aboveembodiments. Moreover, those skilled in the art can change, add andchange each component of the above embodiments easily in the scope ofthe present invention.

From the invention thus described, it will be obvious that theembodiments of the invention may be varied in many ways. Such variationsare not to be regarded as a departure from the spirit and scope of theinvention, and all such modifications as would be obvious to one skilledin the art are intended for inclusion within the scope of the followingclaims.

1. A method of manufacturing a transflective type liquid crystal displaydevice, the method comprising: forming a thin film transistor over afirst substrate; forming an inorganic insulating film to cover the thinfilm transistor; forming an organic film having different filmthicknesses on the inorganic insulating film; etching the inorganicinsulating film exposed from the organic film, to form a contact hole;forming a transmissive electrode and a reflective electrode as films onthe organic film in order; forming a resist pattern having differentfilm thicknesses on the reflective electrode, and etching the reflectiveelectrode and the transmissive electrode; removing, by ashing, a thinfilm portion of the resist pattern, and a thin film portion of theorganic film, exposed from the transmissive electrode, to form anopening; forming a pixel electrode connecting to the thin filmtransistor through the contact hole by etching the reflective electrodeby using the resist pattern left after the removal of the thin filmportion; and bonding the first substrate and a second substrate arrangedoppositely to the first substrate in such a manner that a sealingmaterial in a shape of a frame surrounding a display area is arranged inthe opening of the organic film.
 2. The method of manufacturing atransflective type liquid crystal display device according to claim 1,wherein, at a side of the first substrate, the sealing material isbonded to the inorganic insulating film in the opening.
 3. The method ofmanufacturing a transflective type liquid crystal display deviceaccording to claim 1, wherein multi-level exposure is used in theforming the organic film having different film thicknesses and theforming the resist pattern having different film thicknesses.
 4. Themethod of manufacturing a transflective type liquid crystal displaydevice according to claim 1, wherein, in the forming the organic filmhaving different film thicknesses, a film thickness of the thin filmportion of the organic film is formed to be thinner than a filmthickness of a thick film portion of the organic film, exposed from thetransmissive electrode, to be removed by the ashing.
 5. The method ofmanufacturing a transflective type liquid crystal display deviceaccording to claim 1, wherein the opening of the organic film is formedto surround a display area.
 6. A transflective type liquid crystaldisplay device comprising: a first substrate including a thin filmtransistor formed thereover; a second substrate arranged oppositely tothe first substrate; a sealing material, formed in a shape of a framesurrounding a display area, to bond the first substrate and the secondsubstrate; an inorganic insulating film to cover the thin filmtransistor over the first substrate; an organic film formed on theinorganic insulating film; and a pixel electrode including atransmissive electrode provided on the organic film and a reflectiveelectrode provided on a part of the transmissive electrode, and thepixel electrode connecting to the thin film transistor through a contacthole penetrating the organic film and the inorganic insulating film,wherein the organic film includes a thick film portion provided underthe reflective electrode, a thin film portion formed outside of thetransmissive electrode and having a film thickness thinner than a filmthickness of the thick film portion, and an opening, and the sealingmaterial is arranged in the opening.
 7. The transflective type liquidcrystal display device according to claim 6 further comprising: a gateline formed of a same layer as a layer of a gate electrode of the thinfilm transistor; and a source line formed of a same layer as a layer ofa source electrode of the thin film transistor, wherein the gate lineand the source line are covered with at least the inorganic insulatingfilm, under the sealing material.
 8. The transflective type liquidcrystal display device according to claim 6, wherein the opening isformed to surround a display area.